The present invention relates to a chair, and especially, to a chair suitable for operation of office automation equipment such as a personal computer and keeping stable posture in reclining of an operator.
There is a known chair which has a device for inclining or a seat or the back to support a human body suitably depending on various postures in desk working by office automation equipment such as a personal computer.
In such chairs, an upper portion of the back is kept at the same angle as backward inclination whenever the back is inclined rearwards, or a parallelolink mechanism is included in which an upper portion of the back is always inclined regardless of a reclining angle of the back.
However, in the former chair, when inclined rearwards, a position of one's head is moved rearwards, thereby making it difficult to look at a display of the personal computer. When one is leaned over the back, one's eye is directed upwards. It is said to be suitable as an angle for looking at a monitor display on a desk that one's eye is directed downwards at 5 to 10.degree. . To take such posture in a conventional chair, one's head must be raised upwards, which causes stiff back or weariness in neck.
When one's head is raised forwards forcibly, the back of the human body does not fit with the back of the chair, and the human body is separated from the back of the chair, so that one's posture is placed in unstable situation. Thus, one could not take stable posture and will be tired.
In the latter chair, regardless of reclining angle of the back of the chair, the upper portion of the back must be kept at the same angle. Thus, when the back of the chair is reclined, the person will be humpback and placed under pressure.
To prevent a gap between the back of a human body and the back of the chair in backward posture to cause backache, International Pub. No. WO96/125072 discloses a chair in which the back and buttocks are independently supported regardless of inclination of the backbone or sitting posture. However, buttocks and back receivers are independently inclined by respective mechanism, so that fitness of the back and buttocks of the human body to the back of the chair is lost. Also, the inclining mechanism becomes complicate and is expensive.